Comet 3I/ATLAS is making headlines as it brightens while passing behind the sun. It’s set to reach its closest point to the sun on October 29. While many wait to see it, some researchers and amateur astronomers have been tracking its journey using advanced spacecraft.
On October 18, amateur astronomer Worachate Boonplod used images from NOAA’s GOES-19 weather satellite to spot the comet. He pointed out that it was visible and expected to be tracked until October 24. Boonplod described its brightness as similar to nearby stars, with a magnitude of around 11, which means it’s faint but detectable with good equipment.
Other satellites, including NASA’s Solar and Heliospheric Observatory (SOHO), are also observing 3I/ATLAS. SOHO’s instrument blocks out the sun to help study structures in its atmosphere, focusing on the comet until October 26.
Recent findings published on arXiv indicate that 3I/ATLAS has brightened rapidly leading up to perihelion. It could reach a magnitude of 9, making it faintly visible through a backyard telescope if conditions allow. The study found that the comet was noticeably bluer than the sun, suggesting that gas emissions contribute to its brightness as it nears the sun.
3I/ATLAS, discovered in July, is only the third interstellar comet recorded. It’s flying through our solar system at speeds over 130,000 mph (210,000 km/h) in a remarkably straight path. Some people speculated it might be an alien spacecraft, but astronomers generally agree it’s a natural cosmic object from an unknown star system.
This comet has the highest speed ever recorded for a solar system object. It has likely been traveling for billions of years, gaining momentum as it passed various stars and galaxies, according to NASA. Some estimates suggest that 3I/ATLAS could be around 3 billion years older than our 4.6 billion-year-old solar system. Researchers are still determining its size, but data from the Hubble Space Telescope suggests it could be about 3.5 miles (5.6 km) wide, making it potentially the largest interstellar object observed.
Observers can expect to see 3I/ATLAS again with Earth-based telescopes by early December, and it may even be visible to spacecraft near Jupiter as it approaches the planet in March 2026.
